The Mail was successful because it managed to gain the Prime Minister’s backing, according to Nick Williams, senior partner and head of public affairs at FleishmanHillard.

"Without this coalition of support internet companies would never have changed their position," he claimed.

Schmidt wrote that Google had put more than 200 people to work on tackling the problem over the past three months, following a speech by Cameron in the summer.

The measures announced by Schmidt include a new way of identifying and blocking child abuse videos that Google plans to make available to other internet companies and child safety organisations.

Schmidt wrote that Microsoft deserved a lot of credit for developing and sharing its picture detection technology.

James O’Keefe, founding partner of Tetra Strategy, said: "Just because you’re an online business doesn’t mean society doesn’t have the same expectations of you as any other. I think these companies are starting to realise that and that is to be encouraged."